Modern firearms typically include a mechanical safety that can be engaged to prevent the discharge of the firearm by preventing the trigger from being depressed and/or the firing pin from being released. The safety mechanism often comprises a lever, button or toggle switch on the exterior of the firearm that can be moved by the user with their fingers to engage or disengage the safety mechanism. The safety switch is typically positioned proximate to the user's trigger hand such that the user can disengage the safety and pull the trigger with the same hand while still supporting the firearm.
As depicted in FIGS. 1A-4, the positioning of the safety switch is often such that the user must shift the grip of their trigger hand to provide sufficient leverage to actuate the safety switch from the fire position to the safe position. FIG. 3 illustrates from above the right hand gripping the pistol grip in a firing position. FIG. 4 illustrates the right hand rotated clockwise so that the thumb, specifically the thumb knuckle, can engage the front side of the safety switch lever and pull it backward and upward to the safe position. The safety switch requires a relatively substantial force to bias the switch and typically requires that the switch be rotated at least 90 degrees to avoid accidental disengagement of the safety mechanism requiring the user to significantly readjust their grip to provide sufficient force to the selector switch as depicted in FIGS. 3-4. This arrangement provides additional safety by physically separating the trigger mechanism from the safety mechanism requiring at least two distinct and separate motions to disengage the safety and fire the firearm. Moreover, the user typically is required to reposition their grip from the firing position to a secondary position to apply sufficient force to the safety switch. An inherent drawback of this arrangement is that the readjustment of the user's hand slows the user's operation of the firearm and can impact the accuracy of the firearm.
With rifles, a user typically grips the firearm with one hand proximate to the trigger and supports the barrel with their other hand. Adjusting the grip of either hand will change the orientation of the firearm requiring the firearm to be re-aimed at the target. With the trigger hand, the user must also return their trigger finger to the proper position in addition to re-aiming the firearm to accurately use the firearm. If the trigger finger is not properly positioned, the resulting trigger pull may affect the accuracy of the firearm even if the firearm is properly re-aimed. Accordingly, the required adjustment of the user's trigger hand to operate the safety mechanism also requires that the user re-aim the firearm and reposition their trigger hand in the proper firing position.
Conventional rules of safe firearm operation typically require that the safety mechanism remain engaged until immediately before the firearm is fired. In certain combat, policing or home defense situations, the user may be required to train the firearm on the target with the safety engaged to avoid accidental discharge unless the situation changes to require use of the firearm. And in many cases the safety should be reengaged while the firearm is trained on a target. The repositioning of user's trigger hand to disengage the safety before returning the trigger hand to the proper position and re-aim the firearm can substantially slow the user's operation of the firearm and often require reacquisition of the target. It would be highly advantageous to be able to disengage and engage the safety without having to readjust the gripping of the firearm and without having to re-aim the firearm. As these situations are often highly dangerous, any delay introduced by the repositioning of the user's trigger hand and re-aiming or reacquiring a target can present a substantial risk to the user.
In particular, with the AR-10 and AR-15 style of firearms, the safety is operated by a linear thumb lever that is positioned above and generally rearward of the grip of the firearm and can be rotated with the thumb of the user's trigger hand to engage or disengage the safety mechanism as depicted in Prior Art FIGS. 1A to 4. The thumb lever comprises a circular flat plate, the circular flat plate having an exposed planar surface, parallel to the side wall surface of the lower receiver of the firearm. The circular plate being coaxial with an operative safety shaft connected thereto and extending into the lower receiver and trigger mechanism, the operative shaft normal to the side wall surface. A linear arm extends from the circular shaft along the side wall surface of the lower receiver of the firearm. The linear arm perpendicular to the operative shaft extending into the lower receiver. The linear arm unitary with the circular plate and being slightly spaced from the side wall surface of the lower receiver. The linear arm having a primary longitudinal arm axis and a height of about 0.240 to 0.270 inches measured in a direction perpendicular to the side wall surface of the lower receiver and a length of 0.600 to 0.750 inches in a direction perpendicular to the axis of the operative shaft and parallel to the side wall surface of the lower receiver, and a thickness measured perpendicular to the length and in a direction parallel to the side wall surface of the lower receiver of 0.200 to 0.250 inches. The linear arm is generally rounded about an axis extending in the direction of the length of the arm and on the ends of the arm. The surface of the arm confronting the side wall surface being flat and parallel to the side wall surface. Ridges may extend lengthwise along the arm providing a gripping surface. The arm rotates the operative shaft clockwise and counterclockwise along a 90° arc to operate the safety mechanism. Typically, the lever is oriented such that the arm is horizontal and pointed toward the rear of the firearm when the safety mechanism is engaged and downward and vertical with the safety is off and the firearm ready to fire. The circular plate may have arrow structure or indicia pointing in a direction opposite the direction in which the arm is extending from the circular plate. The entire exposed length of a conventional AR safety, including the circular plate and arm may be about 1.00 to 1.20 inches. The circular plate may have a diameter of about 0.40 to 0.51 inches and a thickness of about 0.050 to 0.065 inches. The thumb lever is positioned such that the user can easily pivot or rotate their thumb upwards and rearward to engage the arm with the inside of the thumb anywhere between the first and second knuckles without altering the grip of the three lower fingers and the heel of the trigger hand. The downward rotation of the thumb effectively returns the user's hand to the original firing position. The heel of the thumb may slightly separate from the back of the grip. In that the grip is primarily secured in the hand by the three lower fingers wrapped there around, the security of the grip is maintained and the firearm need not be re-aimed or the target reacquired.
In contrast, rotating the switch back to the safe position can be far more problematic. Typically, the vertical orientation of the lever arm makes the lever arm difficult to engage with the thumbnail side or upper side of the knuckle without requiring the user to substantially readjust their grip. Moreover, the substantial force required to rotate safety mechanism can result in only partial rotation of the safety mechanism if the user does not properly grip the arm leaving the user believing that the firearm is safe when in fact the safety mechanism has not been engaged. Similarly, depending on the size of the user's hand, the must often reach forward with their thumb to engage the arm against the tip or enough of the front side of the arm to apply sufficient force to rotate the arm. The substantial readjustment of the user's grip can force the user to release or readjust their grip to safely engage the safety mechanism. A similar consideration is that certain users are unable to extend their trigger finger to take the trigger finger off the trigger The linear lever arm of the AR family of firearms typically requires that the user change their grip to operate the safety of the firearm, pulling the sight away from the line of sight of the user and causing loss of target acquisition, thus requiring re-aiming for further shooting and slowing the operation of the firearm. As AR-type rifles are commonly used in military and policing applications, improved functionality of the firearm safety mechanism could enhance safety and efficiency.
As such, there is a need for a means of permitting effective operation of a safety on AR style firearms without requiring the user to readjust the grip of their trigger hand.